Railroad tank cars have, in the past, been equipped with spargers and/or agitators for effecting a thorough mixing of liquid and pulverulent materials prior to discharging the resulting solution or suspension from the tank. These devices were costly and complicated, involving complex piping within the tank, conveyor screws, agitating devices, with the attending maintenance costs and malfunctioning. Certain types of materials were not adaptable to this type of handling due to the formation of large floating chunks. A phenomenon called "dilation" also causes partial solidification of a high solids content slurry.
U.S. Pat. No. 3,451,724 describes a transportable tank for dry pulverulent materials with inlets and outlets to which conduits of a conduit complex are detachably connected for sparging the tank. This type of operation depends primarily upon a recycle in which solution is pumped from the bottom of the tank back up into the top thereof. The recycle is accompanied with a withdrawal at the outset of the operation of a relatively dilute solution from an upper level of the tank which is pumped into the bottom of the tank in a continuous cyclic operation.
Certain types of pulverulent materials, such as dicarboxylic acids, particularly adipic acid are prepared in the form of crystals which are ordinarily wet from a water wash. In the shipment of such materials, in the as-recovered wet form, it would be a significant advance in the art if the unloading of such materials could be simplified by the elimination of one or more of the apparatus essentials or process requirements described in the aforesaid U.S. Pat. No. 3,451,724.